Timed bigraphs for formal verification of sensor network routing protocols

Albalwe, Maram Mohammed Shaher (2025) Timed bigraphs for formal verification of sensor network routing protocols. PhD thesis, University of Glasgow.

Abstract

Given that more end-user applications depend on the Internet of things (IoT) technology, which relies heavily on wireless sensor networks (WSNs), it is essential that the routing protocols underpinning these applications are reliable. Using formal methods for reasoning on protocol specifications is an established technique but, due to their perceived difficulty and mathematical nature, they receive limited use in practice. This thesis proposes an approach based on Milner’s bigraphs – a flexible diagrammatic modelling language – that allows developers to “draw” the protocol updates as a way to increase the use of formal methods in protocol design. Bigraphical reactive systems (BRSs) are a graph-rewriting formalism describing systems evolving in two dimensions: spatially, e.g. a person in a room, and non-spatially, e.g. mobile phones communicating regardless of location. To show bigraphs in action, this thesis models part of the routing protocol for low-power and lossy networks (RPL), popular in wireless sensor networks. The model is implemented using the BigraphER toolkit and verified with the PRISM model checker.

Simulation, on the other hand, is a common approach in the field of protocol analysis and validation. However, it does not extensively verify protocols in the same way as formal methods do. This thesis experimentally compares the two approaches, the results of which show that analysing the bigraph model often finds more valid routes than simulation while providing comparable performance. The bigraphs model is open to extension with less implementation effort than simulation, which is shown by adding more features to the initial model. Bigraphs seem to be a promising approach for protocol design; this is the first step in promoting their use.

Despite the use of bigraphs in domains that include communication protocols, agent programming, biology, and security, there is no support for real-time systems. Therefore, this thesis extends BRSs to support real-time systems by using a modelling approach that employs multiple perspectives to represent digital clocks. It uses Action BRSs, a recent extension of BRSs, where the resulting transition system is a Markov decision process (MDP). This allows a natural representation of the choices in each system state: to either allow time to pass or perform a specific action. The effectiveness of this approach is demonstrated using examples, including extending the RPL initial model with timed aspects using the BigraphER toolkit.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Supported by funding from the University of Tabuk.
• Subjects: Q Science > QA Mathematics > QA75 Electronic computers. Computer science; T Technology > T Technology (General)
• Colleges/Schools: College of Science and Engineering > School of Computing Science
• Funder's Name: University of Tabuk
• Supervisor's Name: Sevegnani, Dr. Michele
• Date of Award: 2025
• Depositing User: Theses Team
• Unique ID: glathesis:2025-85016
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 08 Apr 2025 15:28
• Last Modified: 09 Apr 2025 08:03
• URI: https://theses.gla.ac.uk/id/eprint/85016

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